1. Technical Field
The present application relates to a method and device for adjusting heights of a slitter blade provided in a slitter scorer for scoring and slitting a corrugated board web in a corrugated machine for manufacturing a corrugated board sheet.
2. Background Art
The corrugated board web being continuously produced along a corrugating line, is slit some boxes-out by the slitter blades near a final step of the corrugating line, and if specified, additionally formed with scorer lines thereon by the scorer rolls along the traveling line of the web. Each of the divided webs is cut along the width thereof (perpendicular to the traveling direction of the corrugated board web) by a rotary cutter, being processed into a corrugated board sheet of a specified size and being stacked into a stacker located on a downstream side of the rotary cutter.
FIG. 6 illustrate a latter part of the structure of a general corrugated machine. A corrugated board web W a top liner and a bottom liner on both sides of a corrugating medium by a single facer not shown in the figure and a double facer 2, being formed with scorer lines along a traveling direction b of the corrugated board web by a scorer unit 3 located on the downstream side of the double facer 2, and further being slit along the traveling direction b by a slitter unit 1.
The corrugated web is cut into corrugated board sheets S by a specified length of a product each (usually corresponding to the size of a corrugated board) by a cutting unit 4 on the downstream side of the slitter unit 1, and stacked into a stacking unit 5. The scorer unit 3 and the slitter unit 1 together are usually referred to as a slitter scorer.
The scorer unit forms scorer lines on the corrugated web W along the traveling direction thereof and the slitter unit 1 slits the web W at a specified position along the traveling direction b. The structure of the slitter unit is explained in reference to FIG. 7. FIG. 7 is a side view of the slitter unit along the line X-X of FIG. 6. As shown in FIG. 7, the slitter unit 1 is assembled with frames 10 on both sides thereof, and a beam 11a is installed with respect to the width direction of the corrugated web W (in the direction perpendicular to the traveling direction of the corrugated web W) between the frames 10 below the web W.
A guide rail 12a is mounted on the beam 11a and a plurality of slitter heads 13 (five slitter heads in FIG. 7) are supported on the guide rail 12a in such a manner that they can move in the width direction of the unit by a driving device 14a on each individual slitter head. A slitter blade of a thin disk-shaped rotating blade is rotatably attached to each of the slitter heads 13.
Above the corrugated board web W, a beam 11b is provided in parallel to the beam 11a. A guide rail 12b is mounted on the beam 11a and a plurality of receiving rolls 16 as many as the slitter heads 13, are supported on the guide rail 12b in such a manner that they can move in the width direction of the unit by a driving device 14b on each individual slitter head.
Each web slitting device comprises sets of the slitter blade 15 and the receiving roll 16, and the slitter blades 15 and receiving rolls 16 are independently movable to a specified position in the width direction of the web so as to engage with each other so that the corrugated board web W fed between the sets is cut at positions of a specified width.
Moreover, the rotation speed of the slitter blade 15 is set to be sufficiently faster than the traveling speed of the corrugated board web W so as to perform a clear slitting. Furthermore, the rotation speed of the receiving roll 16 is set to be approximately equal to and slightly faster than the traveling speed of the corrugated board web W so as not to reduce the traveling speed of the corrugated web W.
FIG. 8 illustrates a side view of a slitter head part. In FIG. 8, above the slitter head 13, a receiving table 17 extending in the traveling direction of the corrugated web W is provided integral with the slitter head. The receiving table 17 supports the corrugated board web W from underneath thereof and helps determining the level of a traveling path of the corrugated board web W.
As shown in FIG. 9, the receiving table 17 is positioned at such a height that a circular outer edge 15a of the slitter blade 15 protrudes through the receiving table 17 by a protrusion amount h.
The corrugated board W is slit from underneath by the rotating slitter blade 15. In this process, the edge of the slitter blade 15 is driven in such a manner that the rotation speed of the blade 15 is sufficiently faster that the traveling speed of the corrugated web W at an engaging point where the blade 15 and the web W come in contact with each other. When slitting the corrugated board web W, the rotation of the slitter blade 15 adds the corrugated board web W a force in the upward direction and the traveling direction thereof, thereby causing flipping of the corrugated web W and riding of the web W onto the slitter blade 15.
As the flipping and riding-up of the corrugated web W lowers the slitting quality of the web W, the flipping and riding-up of the web W is prevented in such a way that the receiving roll 16 presses down the corrugated board web W, thereby improving the slitting quality of the corrugated board web.
Moreover, as shown in FIG. 8 a groove 16a is carved on the outer circumference of the receiving roll 16, and an adequate clearance is secured so as not to allow interference of the edge of the slitter blade 15 and the outer circumference of the receiving roll 16 with each other. In this manner, wear of the receiving roll 16 caused by the contact with the slitter blade 15 is prevented.
As FIG. 9 illustrates, the position of the conventional slitter blade 15 is controlled by adjusting the protrusion amount h of the slitter blade 15 above the receiving table 17. Specifically, the protrusion amount h is determined by placing the slitter blade 15 against a jig with a predetermined dimension, which is preliminarily mounted on the receiving table 17.
The slitter blade 15 needs to be sharpened as the edge of the blade 15 becomes worn. As shown in FIG. 9, according to the conventional method, sharpening the slitter blade 15 reduces the radius of the slitter blade 15 (15→15′), and causes the engaging point of the blade 15 and the receiving roll 16 to change from a1 to a2 although the protrusion amount h of the blade is constant. Thus, there occurs a problem that the engaging point is not adjustable even if the protrusion amount h of the blade is controlled.
Related Patent 1 (JP2004-330351A) discloses a means for slitting a corrugated board web in a steady manner wherein radii of circular slitter blades, which become smaller due to wear from regular usage or being sharpened, are measured, the height position of the slitter blade being corrected in accordance with the measurements, and engagement amount of the receiving roll and the slitter blade being properly secured.
This conventional means for slitting the corrugated board web comprises an optical sensor having an optical axis in a parallel relationship with respect to the surface of the corrugated board web, wherein the slitter blade is moved in the vertical direction to interrupt the optical axis, the radius of the slitter blade being calculated from the measured position of the slitter blade, and the slitter blade being moved in the vertical direction according to the results of the calculation, thereby controlling the depth of the engagement of the receiving roll with the slitter blade
The means disclosed in Related Patent 1 includes the step for calculating the radius of the slitter blade, which complicates a control system thereof and creates higher cost. Moreover, depending on the precision of the control system, there may be an error in calculating the depth of the engagement of the slitter blade and the receiving roll and an optimal depth of the engagement cannot be attained. Furthermore, the means of Related Patent 1 merely controls the depth of the engagement between the receiving roll and slitter blade and is not capable of controlling an engaging point between the receiving roll and slitter blade.